For more intermediate steps see Figures 2.11 and 2.13. Q5. Methyl hexanoate. Q6.

pro-R

pro-S

Note that 2-deuterioacetic acid is not pro-chiral, according to the priority rule, because replacing another hydrogen by deuterium means there is one 'H and two 2Hs on the methyl group.

Chapter 3

Ql. Acetyl-S-ACP to malonyl-S-ACP to stearic acid, desaturated to oleic acid, chain extended by three acetate units to a C24 unsaturated acid, and decarboxylation gives (Z)-9-tricosene.

Q2. As for question 1, as far as stearic acid, then addition of one propionate (= methylmalonate) unit and two more acetate units gives 6-methyl-tetradecanoic acid. Decarboxylation gives 5-methyltricosane.

Q3. Palmitic acid is converted to (E)-11 -hexadecenoic acid, then chain-shortened to 9-hexadecenoic acid, and again desaturated by a All-desaturase to (9E,\ l£)-tetradecadienoic acid. The remaining steps are obvious.

Q4. Three deuterium atoms in 9-hydroxydecenoic acid and two in 10-hydroxydecenoic acid.

Q5. The 2-fluoro-atom blocks the first stage of chain-shortening of stearic acid so the whole process is halted.

Q6. Nine of the ten deuterium atoms would remain.

YCD-CpAOH — D3C.C„CD Aoh — -D^CD. °2 nh2 ft D2

D10-isoleucine D9-14-methylhexadecanoic acid

Q7. Bruchin A appears to be made from oleic acid by chain extension with two more acetate units and reduction to the alcohol to give docosanol, which is co-oxidized to an alcohol at the other end of the chain (not necessarily in that order). The 3-hydroxypropionic acid (hydracrylic acid) is an unusual metabolite, with no obvious precursors. It is possibly made here by co-oxidation of propionic acid. Both C22 and C24 diols are found in the mixture from the insect.